As examples of high-performance rare-earth magnets, Sm—Co magnets and Nd—Fe—B magnets are known. In these magnets, Fe and Co contribute to increase in saturation magnetization. Further, these magnets contain rare-earth elements such as Nd and Sm, which bring about large magnetic anisotropy originating in behaviors of 4f electrons of the rare-earth elements in crystal fields. Thus, large coercive force is obtained, realizing a high-performance magnet.
Such high-performance magnets are mainly used in electronic apparatuses such as motors, speakers, and measurement instruments. In recent years, demands for size and weight reduction and low-power consumption of various types of electronic apparatuses have been increasing, and in order to respond to them, permanent magnets of higher performance are demanded, in which a maximum magnetic energy product (BHmax) of permanent magnet is improved. Further, in recent years, a variable magnetic flux motor has been proposed, contributing to increase in efficiency of motors.
The Sm—Co magnets have a high Curie temperature and hence allow realizing good motor characteristics at high temperatures, but are desired to further have higher coercive force and higher magnetization and be further improved in squareness ratio. Since it is conceivable that increasing concentration of Fe is effective to high magnetization of the Sm—Co magnets, conventional manufacturing methods have a tendency to decrease the squareness ratio by increasing concentration of Fe. From these points, in order to realize a magnet for high-performance motors, technology which enables exertion of a good squareness ratio while improving the magnetization in a high Fe concentration composition is needed.